The invention relates to high density, multi-conductor ribbon cable and connectors for high speed electrical signal transmissions. In particular, the invention relates to this type of cable where the spacing between centers of the conductor wires may be varied at different lengths of the cable so that mechanical and electrical characteristics may be matched to those of external devices such as input or output devices or terminal connectors.
Previously, multi-conductor ribbon cable has been manufactured with the space between the centers of the conductor wires specified in order to meet the requirements of the terminal connectors. In one type of connector, insulation displacement connectors (IDC), this spacing may range from 100 mils to 25 mils. The electricals of the cable is determined by the spacing of the conductors as required by the IDC. Other multi-conductor ribbon cable with different spacings can be terminated and connected to terminal connector by using a printed circuit board (PCB). The PCB makes the transition from the spacing of the conductors of the ribbon cable to the connector spacings. However, with the advent of miniaturized electronics equipment, connectors are being reduced in size. For the IDC cable to match the connector size, the electrical impedance of the cable will be further reduced as the conductors move closer together. The increased capacitance may degrade the signal quality in many cases. In many other applications, a ribbon cable may be attached between an output device and an input device. The impedance of the output and input devices may be different. In many applications, it is desirable for the cable to be terminated with an impedance which matches the associated output or input devices. In prior multi-conductor ribbon cable, the constant spacing of the conductor along the cable length fixes the impedance characteristic, and it is the same at both ends of the cable. This means that there will be a mismatched impedance at one end of the cable with the associated input or output device. For example, U.S. Pat. No. 4,143,236 discloses a multi-conductor ribbon cable wherein the center spacings of the signal conductors are fixed by weaving warp and weft yarns in a fabric which fixes the spacing of the signal conductors to produce a controlled impedance characteristic. However, the spacing of the conductors is constant along the length of the cable so that the impedance at the ends of the cable is essentially the same.
Accordingly, an object of the invention is to provide a multi-conductor ribbon cable in which a center spacing of the conductors may be varied along the length of the cable to provide desired mechanical and/or electrical characteristics.
Another object of the invention is to provide multi-conductor ribbon cable having different center spacings of the conductors to mechanically meet the specifications of an electrical connector in which the cable is being terminated.
Another object of the invention is to provide a multi-conductor ribbon cable having conductors with different center spacings at the terminal ends of the cable to match different mechanical and/or electrical characteristics of associated input and output devices.
Another object of the invention is to provide a multi-conductor ribbon cable having a greater center spacing of the signal conductors in an intermediate body portion of the cable than at the terminal ends of the cable.
Another object of the invention is to provide a high density multi-conductor ribbon cable having a variable center spacing of the conductors along its length so that the cable may be contoured to meet mechanical specifications demanded by routing the cable in an associated chassis.
Another object of the invention is to provide a woven high density multi-conductor cable in which the center spacing of conductors is fixed by a woven fabric which may be varied and the tightness of the weave may be varied depending on the number of conductors in that portion of the fabric.